Is acetylene lighter than air

Answer 1

No, Acetylene is heavier than air. In fact for this reason most countries do not allow its use for welding in confined spaces.

Because in the past, leaking acetylene cylinders have filled up the bottom of the area to be welded, with explosive results.

Actually it is slightly lighter than air. Air is roughly 79% Nitrogen and 21% Oxygen. Both Oxygen and Nitrogen exist naturally as homo-nuclear diatomics N2 and O2. Nitrogen has a molecular weight of 28.0 amu(Atomic Mass unit). (14.0 amu x2) Oxygen has a molecular weight of 32.0 amu. (16.0 amu x2)

28.0 amu x0.79 + 32.0 amu x0.21 = 29.0 amu

the effective average molecular weight of air is 29.0 amu

Acetylene has a molecular weight of 26.0 amu.

[Acetylene=HC2H, C=12.0 amu, H=1.01 amu, (12.0 amu x2+1.01 amu x2=26.0 amu)]

26.0 amu < 29.0 amu thus acetylene is roughly 10% lighter than air.

Answer 2

Yes, acetylene is lighter than air. It has a lower density than air, which causes it to rise when released. This property makes it a potential hazard as it can accumulate in high spaces or ceilings if not properly handled.

Answer 3

The answer here us WRONG!

All references by companies that produce actelyene say the specific gravity is .9. Lighter that air. It rises. I does not fall